JPH11118775A - Ultrasonic inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automate an inspection process by extracting the shape of an object with the internal reflection echoes of an object to be inspected and calculating an area, calculating the ratio of a defective area in the object to the area of the object, and automatically judging whether the object is defective or not. SOLUTION: An ultrasonic transducer 2 that places an object 5 to be inspected in a water bath and transmits and receives ultrasonic pulses to and from the object 5, scans the object 5 by a scanner 6. Ultrasonic beams 3 control the Z position of the scanner 6 by a control signal 1 from a system controller 10 so that a focusing point 4 is located at the part of a defect 15 to be inspected in the object 5. A signal within the set time by a control signal 11 is outputted by a gate circuit 7 and is inputted to a peak holder 9 for detecting signal intensity and a time counter 8 for detecting depth. In the controller 10, the depth of a reflection point is calculated from a sound speed being set to the counter 8 and an input device 14 with the signal of the holder 9 as a signal intensity, information on the signal intensity, the depth, and a position can be displayed, thus automatically judging a defect and hence automating an ultrasonic non- destructive inspection process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic inspection apparatus for non-destructively observing and inspecting internal states such as defects in an object using a focused ultrasonic beam.

[0002]

2. Description of the Related Art In an ultrasonic nondestructive inspection, particularly in an inspection using an ultrasonic imaging apparatus, an ultrasonic pulse of about 1 to 2 wavelengths, which is generally called a pulse echo method, is irradiated onto an object while it is irradiated on the object. It scans and visualizes the time information, intensity information or phase information of the ultrasonic echo signal reflected from the surface and inside of the test object together with the position information, and converts the imaged C-mode image (flat display image) or B-mode image Looking at the (cross-section display image), it is determined whether or not a human is defective.

[0003]

However, the above-mentioned prior art has the following problems. That is, since a human determines whether or not a product is defective, there is an individual difference in the person who makes the determination. Also, even in the same person, the judgment may change depending on the physical condition and the like. There is no quantitative criterion because humans judge from video.

A first object of the present invention is to automate the ultrasonic nondestructive inspection process by automatically and quantitatively determining whether or not a test object is defective. Also,
A second object of the present invention is to provide an appropriate display method as inspection data in an ultrasonic nondestructive inspection process by visually and intuitively displaying the judgment result.

[0005]

In order to achieve the first object, according to a first aspect of the present invention, an ultrasonic beam is irradiated on a test object while scanning the same, and an ultrasonic echo from the test object is emitted. An ultrasonic inspection apparatus including an ultrasonic imaging device that receives a signal, visualizes the signal, and displays the image as a C-mode image.
Means for displaying information on the internal reflection echo of the test object on the mode image, means for extracting the shape of the test object from the C-mode image, means for calculating the area of the extracted test object, Means for calculating the area of a defect contained in the extracted test object; and means for automatically determining whether or not the test object is a defect based on a ratio of the defect area to the area of the test object. And characterized in that: Here, as the information of the internal reflection echo, for example, depth information of an internal defect of the test object, or intensity and phase information of the internal reflection echo is displayed.

In order to achieve the second object, according to a second aspect of the present invention, in addition to the configuration of the first or second aspect, the shape and position information of a test object extracted from a C-mode image are stored. Means for graphic display on a screen separate from the C-mode image, wherein information as to whether the test object is a defect is superimposed and displayed on the test object graphically displayed. . Further, according to a third aspect of the present invention, when displaying a graphic, the size of the test object extracted from the C-mode image is less than 50% of the predicted size of the test object specified in advance. Is removed, and when the size of the extracted test object is larger than 150% of the size of the predicted test object specified in advance, it is displayed that a plurality of test objects cannot be separated. .

[0007]

According to the configuration of the first aspect, it is automatically determined whether or not the test object is a defect. Therefore, the judgment of the defect area with respect to the area of the test object does not involve human judgment. There is an effect that the inspection can be performed based on the quantitative and always constant criterion of the ratio. Further, there is an effect that it is possible to automatically determine whether or not the defect is a bottleneck of automation in the ultrasonic nondestructive inspection process. According to the configuration according to the second and third aspects, the inspection result can be displayed visually and intuitively, so that an appropriate display method can be provided as inspection data in the ultrasonic nondestructive inspection process. There is.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a configuration of an ultrasonic imaging apparatus according to one embodiment of the present invention. In the figure, 1 is a pulser receiver, 2 is an ultrasonic transducer, 3 is an ultrasonic beam, 4 is a focal point of the ultrasonic beam, 5
, A scanner capable of scanning in the X, Y, and Z directions, 7 a gate circuit, 8 a time counter, 9 a peak holder, 10 a system controller, 11 a control signal from the system controller, and 12 a control signal from the system controller. A display device, 13 is a printer, and 14 is an input device.

FIG. 2 shows the scanning state of the ultrasonic beam on the object to be inspected, the reception signal (RF) by the pulser receiver and the gate signal (S) of the gate circuit 7 in each scanning state.
FIG. 6 is a diagram showing a relationship between the data (Gate, FGate). Also, in the figure, 15 is a defect.

In the configuration shown in FIG. 1, a test object 5 is placed in a water tank so as to be inspected by a water immersion method.
The ultrasonic transducer 2 that transmits and receives ultrasonic pulses to and from the object scans the object 5 with the scanner 6. The ultrasonic transducer 2 is connected to a pulser receiver 1 that applies a high-voltage pulse for transmitting an ultrasonic wave and amplifies a received signal. The ultrasonic beam 3 transmitted from the ultrasonic transducer 2 is applied to a control signal 1 from the system controller 10 so that the focal point 4 is located at a defect 15 to be inspected inside the object 5 to be inspected.
1 controls the Ζ position of the scanner 6.

On the other hand, the received signal is amplified by the pulser receiver 1, and the gate circuit 7 outputs a signal within the time gate set by the control signal 11 from the system controller 10. The output of the gate circuit 7 is input to a peak holder 9 for detecting signal strength and a time counter 8 for detecting depth. The system controller 10 uses the output of the peak holder 9 as the signal strength, and sets the output of the time counter 8 and the ultrasonic test object 5 set by the input device 14.
The depth of the ultrasonic reflection point (hereinafter, referred to as signal depth) is calculated from the sound speed in the inside, and is output to the display device 12 or the printer 13 together with the signal strength and the signal depth and the position information of the scanner 6. .

Hereinafter, the first embodiment of the present invention will be described in detail. As a general property of an ultrasonic wave, since it is a sound wave, it propagates through a medium and is reflected, refracted, and transmitted at a boundary surface of the medium, and the ratio varies depending on the acoustic impedance between the media. It is also known that, for example, when an air layer due to a defect such as a crack or separation exists inside a metal, ceramic, or the like, ultrasonic waves are almost totally reflected at a boundary surface of the air layer, and the phase is inverted.

A signal received by the ultrasonic transducer 2 (hereinafter referred to as RF) when a defect 15 exists inside the test object 5
As shown in FIG. 2A, an example of the signal is a signal reflected from the surface of the test object 5 (hereinafter referred to as SSig).
And the reflected signal from the internal defect 15 (hereinafter referred to as FSig)
Can be detected.

In the method of detecting these reflection signals, first, an SSig detection gate (hereinafter referred to as SGa) is added to the time gate 7 in advance by a control signal 11 from the system controller 10.
te). At the same time, the system controller 10 sets a peak detection comparator level in the peak holder 9 via the control signal 11. SG
The signal exceeding the comparison level among the RF signals in the ate is detected by the peak holder 9. Here, the peak holder 9 simultaneously detects the signal intensity and the polarity (+/−) thereof. When SSig is detected by the peak holder 9, the system controller 10 sets the time gate 7 via the control signal 11 to a gate for detecting FSig (hereinafter, FGat).
e). A signal exceeding the comparison level among the RF signals in the FGate is detected by the peak holder 9, and its polarity and the maximum value are held.

On the other hand, the system controller 10
The time when g is detected is read from the time counter 8,
Similarly, the time when FSig is detected is read from the time counter 8 and the difference is calculated in advance. Since the speed of sound in the test object 5 is set in advance via the input device 14, if the calculated time is Δt and the sound speed in the test object 5 is v, a defect from the surface of the test object 5 Depth distance d up to 15
Is

[0016]

(Equation 1) Is calculated. Further, by comparing the detected SSig and the polarity (± sign) of FSig, phase information of the ultrasonic wave can be obtained. Therefore, in FIG.
g and FSig are both detected, and the strength of FSig
Phase / depth information can be obtained.

FIG. 2B shows an example in which no defect exists inside the test object 5. In this case, SSig is detected as described in detail in FIG.
FSig is not detected because there is no signal. Also,
FIG. 2C shows an ultrasonic transducer 2 on a test object 5.
Is shown, and of course, SGate
SSig is not detected because there is no RF signal exceeding the comparator level.

The system controller 10 controls the control signal 1
1 while scanning the scanner 6 in the XY directions
Collect Sig and FSig data. The collected data is displayed on the display device 1 together with the position information of the scanner.
2 is displayed.

FIG. 3 shows a display example of a C-mode image, in which a portion where SSig is not detected on the XY position coordinates of the scanner is shown in gray, and SSig is detected but Fs is detected.
In Sig, portions not detected are shown in white, and portions detected in both SSig and FSig are shown in black. As described above, in FIG. 3, the white or black portion is the test object 5 and the black portion is the defect 15. Here, each area is calculated by counting the number of dots in the detected portion.

Further, the system controller 10 is preset with an area ratio (slice level) for judging a defect. When the slice level is set to k, the C-mode image shown in FIG.

[0021]

(Equation 2) Is determined to be defective.

The present embodiment shows an example in which the present invention is applied particularly in consideration of a case where the present invention is used in an electronic component inspection process.
For example, the present invention is considered to be particularly useful in an ultrasonic nondestructive inspection process of a multilayer ceramic capacitor.
A multilayer ceramic capacitor generally has a rectangular parallelepiped of several millimeters or less, and has a structure in which a multilayer ceramic dielectric and electrodes are bonded. Popular defects of the multilayer ceramic capacitor are delamination, cracks, and inclusion of foreign matter between the layers.

When inspecting a small test object 5 such as a multilayer ceramic capacitor, a plurality of test objects 5 are scanned side by side at a time in order to increase the test efficiency. FIG. 4 is an example of a C-mode image when a plurality of test objects 5 are scanned as described above, and shows 10 test objects 5 from A to J and noise K. When determining a defect from the C-mode image of FIG.
It is necessary to extract the number of the test objects 5. In this embodiment,
Shapes are extracted by numbering each of them by an 8-connection labeling process. Further, at the time of labeling numbering, a negative number is assigned to a black portion (a defective portion where FSig is detected), and a positive number is assigned to a white portion (a portion where FSig is not detected). Defect area ratio

[0024]

(Equation 3) Is calculated by

Hereinafter, the labeling process will be described in detail. The background in the original image (the gray part of the C-mode image in the present embodiment) is 0, points already numbered as Χ are R, and other unconfirmed parts are R. With the label number N = 0, the image is scanned from left to right and from bottom to top. When the scanning point (hereinafter, underlined) is R, the following three cases are classified and processed. Perimeter boundary tracking: When the left side, lower left and right below the scanning point are 0,

[0026]

(Equation 4) In such a case, boundary tracking, which will be described later, is performed, and a number is assigned to a point where the left neighbor is 0. The number is set to N when a point already numbered as に よ っ て is encountered by the boundary tracking, and set to N where N = N + 1 otherwise. However, isolated points are ignored. Raster scanning: When the left neighbor is Χ, that is,

[0027]

(Equation 5) In such a case, the scanning points are numbered as Χ, and all the Rs following the scanning points are set as Χ. Inner boundary tracking: when the left neighbor is 0 and the lower left is X, or
If the left neighbor is 0 and the right below is X,

[0028]

(Equation 6) In such a case, a point where the boundary is traced and the left neighbor is 0 is indicated by a triangle. By repeating the above scanning to the upper right, serial numbers from 1 to N are assigned to all areas on the image.

The following describes the boundary tracking. Since the scanning on the image is performed from left to right, the starting point comes from the left side. That is, when the point of interest is represented by Χ, the moving direction number when eight surroundings are connected is

[0030]

(Equation 7) Then, the starting point is point (4).

Here, points in the direction larger than the number (entrance number) of the direction entering the point of interest (however, (0) after (7)) are examined in order,
Move to there if it is not 0 (background). The moved point is set as a point of interest, and the entrance number is obtained from the moved direction. For example, if you move to (1), the entry number will be (5). The above processing is repeated until the processing returns to the start point (the point indicated by the entrance number (here, (4)) at the start of the boundary tracking of the point of interest X).

As described above, a plurality of test objects 5 are extracted by the labeling process. As described above, a defective portion is numbered with a negative number during labeling, and the other portions are numbered with a positive number.

Next, the calculated result is graphically displayed on a screen different from the C-mode image. For this purpose, for each of the plurality of test objects 5, the area, the center of gravity position, and the inclination angle with respect to the x direction are calculated. In order to calculate these shape features, the following processes are performed for the number of labels, with the numbers having the same labeled absolute value as one set.

Area calculation: The total area is calculated as the number of dots of a label having the same absolute value, and the area of a defective portion is calculated as the number of dots of a negative label. Center-of-gravity position calculation: Assuming that the maximum value and the minimum value in the x and y directions are x _max , x _min , y _max , and y _min , respectively, the center of gravity (x _g , y _g ) is defined as a rectangular or similar object. Assuming

[0035]

(Equation 8) Is calculated. Angle calculation: When the lengths in the x direction and the y direction that can be calculated from are different, the angle is calculated based on the moment feature. The digital figure is represented by f (x, y), and its barycentric coordinates are represented by (x _g ,
y _g ), the central moment around the (p + q) -order center of gravity is

[0036]

(Equation 9) In particular, for an elongated figure, the angle θ between its main axis and the x-axis is

[0037]

(Equation 10) Is calculated. On the other hand, when the lengths in the x direction and the y direction are substantially the same, the point sequence closest to the x axis is linearly approximated by the least squares method, and the arc tangent of the slope of the straight line is calculated. Assuming that an equation of a straight line to be approximated is f (x) = ax + b and the number of point sequences is n, the evaluation function J of the least squares method is

[0038]

[Equation 11] In order to obtain the minimum value of the evaluation function, the partial derivative by the coefficient of the polynomial of J is set to 0. Ie

[0039]

(Equation 12) From these two equations, the slope a of the straight line is

[0040]

(Equation 13) Becomes Therefore, the required angle θ is

[0041]

[Equation 14] Is calculated.

FIG. 5 shows an example of a graphic display based on the calculated features of the extracted figure. Here, the shape is displayed on the graphic screen based on the obtained coordinates and angles of the center of gravity and the size of the predicted test object 5 which is set in advance. In the drawing, D and F show examples in which the ratio of the area of the defect exceeds the preset slice level for determining a defect. Also, A
Indicates an example in which the defect is not judged because it does not exceed the slice level.

K in FIG. 4 is a predicted size 5 of the test object 5 in which the area of the figure whose shape has been extracted is set in advance.
Since it is less than 0%, it is not displayed on the graphic screen of FIG. Also, B and C in FIG.
An example is shown in which the mode screens overlap and cannot be separated. In this case, since the labeling is performed as one set in the labeling process, the area of the calculated figure is set to one of the predicted size of the test object 5 set in advance.
It exceeds 50%, and is shaded in FIG. 5 to distinguish it from other test objects 5.

The graphic display described above is an example, and when a defect is determined or when a plurality of target objects 5 cannot be separated, the display may be performed by changing the color or the size. Needless to say.

(Second Embodiment) In the first embodiment, the case where FSig is detected is regarded as a defect, but the judgment of the defect is not limited to this. For example, FGa
When te is set to include a signal from the back surface of the test object 5, if the ultrasonic transducer 2 is located at the position (B) in FIG. 2, it becomes (B '), and FSig is detected. However, as described in the first embodiment, since the distance d from the surface of the test object 5 to the portion where FSig is detected is calculated, the distance is displayed on the C-mode image, and the distance d is displayed. May be determined as a defect only when is within a predetermined range. Similarly, when an air layer exists due to a defect such as a crack or separation inside the test object, the phase information and the intensity information are displayed on the C-mode image because the phase of FSig is inverted.
Only the case where the phase is inverted and the intensity is within a predetermined range may be determined as a defect.

(Third Embodiment) In the first embodiment, both the SGate and the FGate are set for the time gate 7, but two time gates and two peak holders are configured in parallel. , SGate and FGate may be set independently to detect SSig and FSig.

[0047]

As described above, according to the present invention,
In an ultrasonic imaging apparatus that receives and echoes an ultrasonic echo signal from a test object, a means for extracting a shape of the test object from a C-mode image, an area of the extracted test object, and the extracted Means for calculating the ratio of the area of the defect included in the test object, and it is possible to automatically determine whether or not the test object is a defect from the ratio of the area. In the destructive inspection process, there is an effect that a quantitative inspection can be performed. Similarly, since the inspection result and data such as the coordinates of the center of gravity and the size of the object to be inspected are also quantitatively collected, for example, data for extracting only a defective product by a robot hand after the inspection can be output. There is an effect that the ultrasonic nondestructive inspection process can be automated.

In addition, the C-mode graphically displays the shape and position information of the object to be inspected and information as to whether or not the object is defective on a screen different from the image, so that the inspection result can be visually and visually confirmed.
It is intuitively understood that there is an effect that work can be performed efficiently even when a defective product after inspection is manually extracted.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus configuration according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between an RF signal and Gate in the device of FIG.

FIG. 3 is an explanatory diagram of a C-mode image in the apparatus of FIG.

FIG. 4 is an explanatory diagram of a C-mode image in the apparatus of FIG.

FIG. 5 is an explanatory diagram of a graphic display screen in the device of FIG. 1;

[Explanation of symbols]

1: pulser receiver, 2: ultrasonic transducer,
3: Ultrasonic beam, 4: Focusing point, 5: Object to be inspected, 6: Scanner, 7: Gate circuit, 8: Time counter, 9: Peak holder, 10: System controller, 11: Control signal, 12: Display device , 13: printer, 14: input device, 15: defect.

Claims (10)

[Claims] 1. An ultrasonic imaging apparatus comprising: an ultrasonic imaging device that irradiates an object to be inspected while scanning an ultrasonic beam, receives an ultrasonic echo signal from the object, visualizes the signal, and displays the image as a C-mode image. In the inspection apparatus, a unit for displaying information of an internal reflection echo of the test object on the C-mode image, a unit for extracting a shape of the test object from the C-mode image, and an area of the extracted test object Means for calculating the area of the defect included in the extracted test object, and from the ratio of the defect area to the area of the test object, whether or not the test object is a defect Means for automatically judging the ultrasonic inspection apparatus. 2. The information of the internal reflection echo is time information until the internal reflection echo returns to the surface of the test object, that is, position information of the internal defect of the test object in the depth direction. The ultrasonic inspection apparatus according to claim 1, wherein: 3. The ultrasonic inspection apparatus according to claim 2, wherein the position information in the depth direction of the internal defect is displayed on the ultrasonic imaging apparatus while changing luminance according to the depth. 4. The ultrasonic inspection apparatus according to claim 3, wherein the background is displayed in gray, the surface of the test object is displayed in white, and the internal defect is displayed in black regardless of the depth. 5. The ultrasonic inspection apparatus according to claim 1, wherein the information of the internal reflection echo is intensity and phase information of the internal reflection echo. 6. The means for calculating the area of the defect includes a point where the intensity of the internal reflection echo is larger than a predetermined value;
6. The ultrasonic wave according to claim 5, wherein a point where the phase information is inverted is a point constituting a defect inside the test object, and a shape of the defect is extracted to calculate an area of the defect. Inspection equipment. 7. The ultrasonic imaging apparatus according to claim 5, wherein the intensity and phase information of the internal reflection echo of the test object is displayed on the ultrasonic imaging apparatus by changing the brightness or color tone according to the intensity and phase. 7. The ultrasonic inspection apparatus according to 6. 8. The ultrasonic inspection apparatus according to claim 6, wherein the background is displayed in gray, the surface of the test object is displayed in white, and the internal defect is displayed in black. 9. A result of displaying the shape and position information of the test object extracted from the C-mode image graphically on a screen different from the C-mode image and determining whether or not the test object is defective. The ultrasonic inspection apparatus according to any one of claims 1 to 8, wherein is superimposed on the object to be graphically displayed. 10. When displaying a graphic, when the size of the test object extracted from the C-mode image is less than 50% of the size of the predicted test object specified in advance, it is removed as noise; When the size of the test object extracted from the C-mode image is larger than 150% of the predicted size of the test object specified in advance, it is displayed that a plurality of test objects cannot be separated. The ultrasonic inspection apparatus according to claim 9, wherein: